by Will Davis
Idaho National Laboratory is celebrating 70 years of operation in the mission of advancing knowledge in the field of nuclear technology. Materials, methods – even basic questions about feasibility of certain concepts – have been tested and proven at this historic, and quite large remote facility in the Idaho desert over all these years. A number of notable firsts have occurred there, including the first operation of a nuclear plant designed for shipboard use (STR, later S1W) as well as tests for the (abortive) nuclear bomber program. Thousands of valuable test hours were racked up by samples in the legendary Materials Test Reactor and its neighbor the Engineering Test Reactor – both now gone, their former sites mostly now a parking lot.
One of the concepts tested for theoretical feasibility at the site – originally, the National Reactor Testing Station – was that of the boiling water reactor. While it seemed fairly obvious and probably workable to have the coolant and moderator boil in the reactor core itself, there were many questions about stability and about transient behavior of the core of such a design. The NRTS was just the place needed to perform the experiments required to prove out the ideas being developed (mostly at Argonne National Laboratory.)
To that end, the Boiling Reactor Experiments (BORAX) were begun in 1953 at NRTS with the construction of a 1.2 MWt experimental reactor contained in a mound not far from the site of the historic Experimental Breeder Reactor 1. The arrangement of the BORAX-I reactor is shown below.
BORAX-1 was operated in a wide range of transient tests, in order to determine how the development of steam voids inside the core during critical operation affected the reactor’s ability to turn power or damp transients. It was found that the reactor was quite